Law enforcement officials believe Bella Martinez is in grave or immediate danger.
Police are looking for 17-year-old Aryel Moreno in connection with her abduction.
Bella is described as a white female, 5'4", 170 lbs, with black hair and brown eyes. Police say she was last seen wearing a black t-shirt with Ice Cube on it, black ripped jeans and black crocs with charms.
Police describe Moreno as a white male, 5'7", 200 lbs, with black hair and brown eyes. He is driving a gold Chevy Impala with a dent on the right side passenger door, according to police.
Moreno was last heard from at 400 Hotwells Blvd in San Antonio around 1:30 p.m. Thursday.
If you have any information regarding the abduction, call the San Antonio Police Department.
The Amber Alert system, used in all 50 states as well as the District of Columbia, Puerto Rico and the U.S. Virgin Islands, was created in 1996. It stands for America's Missing: Broadcast Emergency Response and was created as a legacy to 9-year-old Amber Hagerman, who was kidnapped while riding her bike in Arlington, Texas, and later murdered.
You can view all active Texas Amber Alerts from the Texas Dept. of Public Safety at dps.texas.org.